Amy Dickinson is a general advice columnist.
DEAR AMY: I met a man online 18 months ago. We have a good friendship. We began emailing, which led to our current form of communication -- texting. My problem is that my friend only wants to text or email. We have never talked to each other. I called him once and got his voice mail, which had a man's voice (it had occurred to me that he could be a she, but we have also exchanged photos and addresses). I am fine with text and email, as I don't want to do anything to ruin our friendship. I'm just curious about this. We are both in the 40-54 age range. He has never been married, and I am married. There is no romance going on, just a good friendship. We have conversed by email or text every day since 2013. What are your thoughts about the "no talking" aspect of our relationship?
DEAR WONDERING: You don't mention asking this man why he doesn't want to speak to you; this would be the obvious first place to look for answers.
You also don't mention why you -- you say you're married -- are looking online for new male friendships.
Regardless of your mutual motivations, I think it's possible that he is simply extremely shy; he may fear that voice calls will merge into pressure to meet in person. Or he may avoid phone calls because they are simply less easy to control than text-based communication.
My favorite book about an epistolary relationship is "84 Charing Cross Road" by Helene Hanff (1990 Penguin Books). Hanff was a spunky (unmarried) writer in New York City when she began a lively, lovely and touching correspondence with Frank Doel, a (married) bookseller in postwar London. The two wrote to each other for 20 years before Doel's death. They never met in person, and Hanff maintained a secondary friendship with Doel's wife and daughter.
If your friendship is functional, positive and doesn't negatively affect anyone else, then I'd say you should accept it as it is -- and enjoy it.